Note: Descriptions are shown in the official language in which they were submitted.
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Description
Dynamo-electrical machine with segmented stator structure
and/or rotor structure
The invention relates to a dynamo-electrical machine, in
particular a large dynamo-electrical machine with power
outputs of greater than 1 MW. Said machines are frequently
designed with a segmented structure in order to eliminate
problems of transportation by road and rail. In this case,
either the rotor of the machine, the stator of the machine or
both the stator and the rotor may be designed to be segmented.
Problems arise when assembling these segments during the
assembly of the segments to form a complete stator ring or
rotor ring, due to manufacturing tolerances of the respective
segments. Thus difficulties occur during assembly, for
example, due to the tolerances of the pitch angle of the
segments or by an offset of through-holes of two segments
which are arranged one after another in the rotational
direction of the stator or rotor and which are intended to be
connected together.
Hitherto, during the assembly of the segments, the gaps
produced between the segments were therefore machined, either
in particular by material-removing machining of the gap, for
example, which has a high requirement for accuracy in order to
minimize tolerances, or the gap between the segments to be
connected together was lined with inserts in order to fix the
segments to be connected together by a simple conventional
screw connection. However, this ultimately leads to complex
and awkward operations, in particular during the final
mounting on site.
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Proceeding therefrom, the object of the invention is to
provide a dynamo-electrical machine with a segmented structure
in which the segments of the stator and/or of the rotor of
this dynamo-electrical machine may be assembled in a simple
manner, so that it is possible to compensate for tolerances
and additionally these segments are prevented from shifting
independently.
This object is achieved by a dynamo-electrical machine with a
stator and a rotor which is rotatably arranged relative to the
stator about an axis of rotation, wherein the stator and/or
the rotor has a plurality of segments arranged one after
another in the rotational direction of the rotor, wherein the
segments have a flange at the side ends thereof in the
rotational direction for connection to segments arranged
adjacent thereto in the rotational direction, wherein the
flanges have at least one hole in the rotational direction,
wherein flanges facing one another at the side ends in the
rotational direction of segments arranged adjacent to one
another are connected to one another by a screw connection
passing through a hole, wherein to connect the flanges facing
one another, a sleeve having an external thread is arranged in
the hole of at least one of the flanges facing one another at
the side ends in the rotational direction, wherein the hole of
at least one of the flanges facing one another at the side
ends in the rotational direction has an internal thread,
wherein the sleeve is screwed into the internal thread of the
hole, wherein the sleeve creates a spacing between the flanges
facing one another, wherein a screw passes through the holes
of the flanges facing one another at the side ends in the
rotational direction, and through the sleeve, wherein the
screw, in particular the screw head, exerts a force on the
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flange and via the sleeve connects the flanges facing one
another.
According to the invention, at least one of the flanges facing
one another at the side ends in the rotational direction now
has an internal thread, wherein a sleeve is screwed into the
internal thread of the hole, wherein the sleeve creates a
spacing between the flanges facing one another, wherein a
screw passes through the holes of the flanges facing one
another at the side ends in the rotational direction, and
through the sleeve, wherein the screw exerts a force on the
flange, in particular through its screw head, and via the
sleeve thus connects the flanges facing one another. As a
result, therefore, a particularly simple screw connection is
permitted between two segments to be connected. The support is
now provided on the surrounding flange, so that by the applied
pretensioning the sleeve is prevented from independent
rotation and a connection without clearance is made between
the two flanges or respectively the segments.
If the two holes facing one another have internal threads,
said holes are provided, in particular, with different
diameters.
Moreover, it proves advantageous if the other hole of the
flanges facing one another at the side ends in the rotational
direction also has an internal thread and the screw is screwed
into the internal thread of the other hole. By this measure,
the use of a nut on the screw for fixing the flange may be
dispensed with.
However, with a longer screw, said screw may be inserted
through the second hole and locked by a nut.
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The use of one or more universal ball joints in the gap and/or
on the side of the screw head, which provides further tolerance
compensation and avoids bending moments from the screw, is
particularly advantageous.
A dynamo-electrical machine designed in such a manner may be used
in this case as an electric motor, for example as a drive in tube
mills or as a generator. In this case, in particular, the
application is suitable for wind energy generators, in particular
directly driven wind energy generators. By means of the connection
of the segments according to the invention, it is no longer
essential to carry out highly accurate material-removing machining
of the flanges. This reduces the production costs of such segments.
According to another embodiment of the present invention, there is
provided a dynamo-electrical machine, comprising: a stator and
a rotor rotatable relative to the stator about an axis of
rotation, at least one of said stator and said rotor having a
plurality of segments arranged one after another in a
rotational direction of the rotor, said segments each having
opposing ends facing in opposite rotational directions, and
being provided with flanges on the opposing ends, with
respective flanges of neighboring ones of the segments in
confronting relationship, each of said flanges having at least
one hole oriented in the rotational direction, said at least
one hole of at least one of the respective confronting flanges
having an internal thread and threadably receiving a sleeve
having an external thread, said respective confronting flanges
being spaced apart by the sleeve, wherein a screw having a
shaft and a head is received through the at least one hole of
the one of the respective confronting flanges and through the
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81788238
4a
sleeve and engages in the at least one hole of the other one
of the respective confronting flanges, thereby exerting a
force on the one of the respective confronting flanges and
connects the respective confronting flanges to each other via
the sleeve, wherein the at least one hole of the other one of
the respective confronting flanges has no internal thread and
the screw engages in the at least one hole of the other one of
the respective confronting flanges hole, wherein the force of
the screw exerted on the one of the respective confronting
flanges is implemented via a universal ball joint which
consists of a spherical cup and a spherical disk, said
universal ball joint arranged on the one of the respective
confronting flanges, and a resilient sleeve surrounding only
the shaft of the screw between a head of the screw and the one
of the respective confronting flanges to achieve a clamping
length of the screw and compensate for deviations in
parallelism of bearing surfaces, said resilient sleeve having
a first external diameter and a second larger external
diameter.
The invention and further advantageous embodiments of the
invention are described in more detail with reference to
schematically shown exemplary embodiments, in which:
FIG 1 shows a dynamo-electrical machine according to
the invention in a perspective view,
FIG 2 shows a cross section of a stator of the
dynamo-electrical machine,
FIG 3 shows a longitudinal section of the dynamo-
electrical machine extending through the gap
between two segments,
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FIGS 4 to 9 show very different embodiments of the
connection of two segments by means of a
sleeve.
FIG 1 shows in a perspective basic sketch a dynamo-electrical
machine 1 according to the invention. The dynamo-electrical
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machine 1 has a rotor 5 which is rotatably arranged about a
rotational axis R, said rotor during operation of the dynamo-
electrical machine rotating about the rotational axis R in the
rotational direction S. Moreover, the dynamo-electrical
machine 1 comprises a stator 4 which is arranged in a
stationary manner and which in the context of this exemplary
embodiment is positioned via bearings on a shaft 2 by means of
a supporting device. The stator 4 has segments 4a, 4b arranged
one after another in the rotational direction S of the rotor
5, wherein for the sake of clarity only two segments have been
provided with reference numerals. The segments in this case
are arranged to form a ring. The supporting device 3 connects
the shaft 2 to the segments of the stator 4 via bearings.
Within the context of this exemplary embodiment the dynamo-
electrical machine 1 is designed as a so-called external
rotor, i.e. during the operation of the dynamo-electrical
machine the rotor 5 rotates about the centrally arranged
stator 4.
Alternatively, the dynamo-electrical machine according to the
invention may also be produced as an internal rotor, in which
the stator 4 is also arranged in a stationary manner but
encompasses the rotor 5 in the peripheral direction.
FIG 2 shows in a schematic view a cross section of the stator
4 of the dynamo-electrical machine 1 according to the
invention. The stator 4 has a plurality of segments arranged
one after another in the rotational direction S of the rotor
5, said segments forming a ring when assembled. In this case
only the two segments 4a, 4b arranged adjacent in the
rotational direction S are provided with reference numerals in
FIG 2. Within the context of the exemplary embodiment, in this
case the stator 4 has six segments, wherein the segments have
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a pitch angle a which is slightly less than 60 , so that a gap
is produced between the segments when the segments are
assembled to form the ring. In FIG 2 for the sake of clarity
only the gap 7 is provided with a reference numeral. The
segments are connected together by screw connections to form
the ring, wherein in FIG 2 only one screw connection 6 is
provided with a reference numeral.
Naturally, the segments may also have different pitch angles
a, but ultimately the transportation and the handling at the
installation determine the size of the pitch angle.
In contrast to the prior art, in the present invention the gap
7 between the segments is not lined with material and thus the
gap 7 is not filled in, but the gap 7 is maintained as an air
gap and the flanges 9a, 9b are connected together by a screw
connection according to the invention. The flanges 9a and 9b
which face one another at the side ends 13a and 13b in the
rotational direction of the segments 4a and 4b arranged
adjacent to one another are connected together by a screw
connection according to the invention which passes through the
hole 10a and 10b thereof.
FIG 3 shows a basic view of an external rotor generator in
longitudinal section. A shaft 2 drives the rotor 5, which
interacts electromagnetically with the stator 4 via the air
gap 19 of the dynamo-electrical machine and produces
electrical energy. The stator 4 in this case is supported on
the rotating shaft 2 by a supporting device 3 and by bearings
20.
Permanent magnets are arranged on the rotor 5 opposite the
stator 4. The stator 4 is fastened to the nacelle of the wind
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energy installation via a torque support, not shown in more
detail.
In this case, the flange 9a has a plurality of holes arranged
in the direction of the rotational axis R along the flange,
wherein in FIG 3 only the hole 10a is provided with a
reference numeral. Within the context of the exemplary
embodiment, the screw connection shown according to the
invention is thus repeatedly present in the direction of the
rotational axis R along the flanges of the segments.
However, it should be noted here that in an extreme case, the
flanges may also have just one respective hole which serves to
connect segments arranged adjacent to one another in the
rotational direction S.
In principle, permanent magnets are arranged on the periphery
of the rotor 5 for producing a magnetic field, said permanent
magnets being aligned in the direction of the stator 4. For
reasons of clarity, however, said permanent magnets are not
shown in the figures. Similarly, the winding system present in
the stator 4 is not shown, said winding system being required
to interact electromagnetically with the permanent magnets of
the rotor 5 and thus to function as a drive or generator. The
winding system of the stator 4 and/or of the segment may in
this case be a single-layer winding or double-layer winding
made of form-wound coils which advantageously have the same
winding pitch and on the front faces of the stator 4 represent
a two-stage or three-stage winding.
Advantageously, each segment has a complete winding system,
i.e. after mounting, no coils have to be inserted into the
grooves of the stator 4 which extend beyond the limits of the
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segments. The segment together with its winding system may
therefore be electrically tested, cast, etc. in the factory.
The segments may be connected together at the installation in
the manner according to the invention. Moreover, the
electrical connections have to be produced of the coil starts
and coil ends of the respective phases.
According to FIG 4 the holes 10a, 10b of the flanges 9a, 9b
comprise internal threads ha, 11b. A sleeve 8 comprising an
external thread 8a is screwed into the internal thread 11a,
wherein the sleeve 8 creates a spacing between the flanges 9a
and 9b facing one another. The sleeve 8 has a width and/or an
axial length which is smaller than the width of the flange
plus the width of the gap 7. As a result, the action of the
force of the screw connection may extend to the flange 9b.
A screw 12 passes through the holes of the flanges 9a and 9b
facing one another at the side ends 13a, 13b in the rotational
direction, and through the sleeve 8, the thread 12a of said
screw being screwed into the internal thread lla of the hole
10a of the flange 9a. The screw 12 exerts a force on the
flange 9b and connects the flanges 9a and 9b facing one
another via this introduction of force. By this arrangement, a
gap 7 which is present due to manufacturing tolerances etc.
may be bridged by a non-positive connection and thus "blocked"
and/or fixed.
The action of force is supported on the surrounding flange 9b.
By the pretensioning applied onto the sleeve 8, which is also
denoted as a threaded bushing, said sleeve is prevented from
independently twisting and a connection of the respective
segments 4a, 4b is formed without clearance. Advantageously,
for rotating the sleeve 8 said sleeve may be provided with one
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or more slots on the front face or with an internal polygon,
for example a hexagon or octagon.
FIG 5 shows a further exemplary embodiment of two segments 4a,
4b to be connected together, said segments being offset to one
another. If the bearing surfaces of the screw 12 on the flange
9a are not perpendicular, this produces an additional bending
moment in the screw 12. In order to reduce this effect, in
addition to the known elements such as the sleeve 8 and the
screw 12, a clamping plate 14 is inserted between the head of
the screw 12 and the flange 4a. Thus an additional bending
moment in the screw 12 would be avoided if the boreholes of
the two flanges 9a and 9b were not aligned.
This reduction in the additional bending moment is implemented
by a reduced bearing radius of the head of the screw 12 on a
clamping plate 14. Amongst other things, the clamping plate 14
is also used to compensate for setting losses of the screw
connection 6.
FIG 6 shows in a further embodiment another possibility for
avoiding this additional bending moment in the screw 12. In
this case, a connection of the two segments 4a and 4b is
provided on the bearing surface between the screw head and the
flange 9a by means of a universal ball joint 15 consisting of
a spherical cup 15a and a spherical disk 15b and also a
resilient sleeve 16. Thus any forces which could damage the
screw connection are compensated. For achieving a sufficient
clamping length of the screw 12, a resilient sleeve 16 is
advantageously used. This arrangement also serves, in
particular, to compensate for deviations in the parallelism of
the bearing surfaces.
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FIG 7 shows a further arrangement in which the bending moments
are also compensated. In this case, the universal ball joint
is now attached between the screw head and the resilient
sleeve 16.
FIG 8 shows a similar embodiment to FIG 6 but in this case the
screw 12 is designed to he axially longer so that at the end
of the hole 10b of the segment 4a it may be locked by a nut
17. The hole 10b is in this case designed as a through-hole
without a thread. In this case, the universal ball joint 15
may also be arranged on the nut side.
FIG 9 shows in a further embodiment a screw connection 6 of
two segments 4a, 4b which has a universal ball joint 15 both
in the gap 7, i.e. between the flanges 4a, 4h, and also on the
side of the flange 4a facing the head of the screw 12.
Additionally a resilient sleeve 16 is provided on this side of
the flange 4a facing the screw head. Thus bending moments are
also avoided in the screw 12, said bending moments being able
to be produced in the case of very high alignment tolerances
of the two holes 10a and 10b, as is the case, amongst others,
of surfaces which are oblique relative to one another.
The embodiment according to the invention of the connection of
segments of stators 4 and/or rotors 5 is suitable, in
particular, for wind energy installations or tube mills. With
large diameters of the stator 4 and/or the rotor 5, therefore,
the segments thereof may be transported individually to the
installation and by the connection of these segments according
to the invention it is possible to compensate for tolerances
in a simple manner during mounting. As a result, a uniform air
gap 19 of the dynamo-electrical machine is provided, so that
distortions of the sine-wave form of the current produced by
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Generator are avoided. Moreover, uneven magnetic tractive
forces are avoided and this, amongst other things, extends the
service life of the bearings.
